Students may say a teacher's lesson is boring, a researcher says, when frustration is really what they feel. While boredom is a perennial student complaint, emerging research shows it is more than students' not feeling entertained, but rather a "flavor of stress" that can interfere with their ability to learn and even their health. An international group of researchers argues this month in Perspectives on Psychological Science that the experience of boredom directly connects to a student's inability to focus attention. Boredom is one of the most consistent experiences of school and one that can be frustrating and disheartening for teachers. According to findings in the High School Survey of Student Engagement, conducted by the Indiana University Bloomington, boredom is nearly universal among American students. Of a representative sample of more than 275,000 high school students surveyed in 27 states from 2006 to 2009, 65 percent reported being bored in class at least once a day.